Api upgrade to V5

[MadnessExpress]

I upgraded the API support to V5. I haven't tested everything, but the basic things seem to be working. The README will need some attention.

[schmich]

At first glance, this looks great. Thanks for the contribution!

I was tracking Twitch API updates on GitHub which seems to be abandoned now in favor of their own dev docs, so I completely missed all the new features and changes.

I will go over the changes a bit more, merge them, get the README up-to-date, and push out a new version of the gem.

Thanks again for your help.

[MadnessExpress]

No problem, the API went dead on the 14th, so I figured I might as well try to update this. There are still some other new things that need to get added. Most stuff didn't change too much. One or two endpoints had slight name changes where they went from a singular name to a plural name. The biggest change was everything switching over to ids instead of names, but they built an endpoint to convert names to ids, which I added in, but you might want to see if the way I went about it is sufficient. I am not familiar with spec files, so I didn't make spec files for V5. If I have time I might work on adding the new stuff I did add to the readme.